Chair back



FIG. 1 is a perspective view of a chair back in accordance with our new design, with portions of a chair forming the environment of the chair back and being illustrated in broken lines, which broken lines are for illustrative purposes only and form no part of the chair back;

FIG. 2 is a front elevational view of the chair back shown in FIG. 1;

FIG. 3 is a right-side elevational view thereof, the right and left sides of the chair back being symmetrical to one another;

FIG. 4 is a top plan view thereof;

FIG. 5 is a rear elevational view thereof; and,

FIG. 6 is a bottom view thereof. 

The ornamental design for a chair back, as shown and described. 